The present invention relates to gas generators which can be conveniently installed in airbag devices. In particular, the present invention relates to a gas generator capable of performing gas ejection in multiple stages.
Airbag device to be mounted in fast-moving bodies such as automobiles includes gas generator which is so-called inflator, module cover which covers the airbag, and the like. The gas generator operates to inflate airbag which receives passenger's body when the automobiles encounter emergencies such as collisions.
A gas generator typically includes a cylindrical partition (booster tube) in a container, the cylindrical partition being provided with a detonator (booster propellant) inside the booster tube and a gas-generating agent (main propellant) outside the booster tube.
The booster tube is also provided with an initiator (electrical igniter). The detonator ignites when electric current is supplied to the initiator. When the detonator ignites, gas is ejected from an aperture of the booster tube, the gas-generating agent ignites, a large volume of gas is rapidly generated, and the generated gas is ejected to the outside of the gas generator and inflates an airbag.
A multi-stage-type (multiple-step gas-ejection) gas generator may include a container divided into a plurality of chambers defined by partition plates, each containing a gas-generating agent. The gas-generating agents contained in the plurality of chambers are independently ignited by initiators. Partition plates are each provided with a hole to be coupled with a cylindrical booster tube, and the booster tube is firmly coupled with and welded to the hole.